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Perioperative Blood Transfusion in Anemic Patients undergoing Elective Endovascular Abdominal Aneurysm Repair:Threshold, Timing and Outcomes
Hanaa Dakour Aridi, MD, Besma Nejim, MBChB, MPH, Satinderjit Locham, MD, Widian Alshwaily, MD, Tru Dang, MD, Mahmoud B. Malas, MD, MHS.
Johns Hopkins University, Baltimore, MD, USA.

Introduction: The association between perioperative blood transfusion (Tx) and postoperative morbidity and mortality is unclear.The aim of this study is to evaluate the outcomes of Tx in anemic patients undergoing elective endovascular Abdominal Aneurysm Repair (EVAR).
Methods: A retrospective analysis of patients who underwent elective EVAR in the VQI (2008-2017) was performed. Anemia was defined as moderate/severe (Hb<10 g/dl) or mild (Hb:10-12g/dL in females, and 10-13 g/dL in males).Multivariate logistic regression analysis was used to assess the association between Tx and in-hospital adverse events including mortality, myocardial infarction, acute CHF, dysrhythmia, stroke, renal failure, leg and bowel ischemia, respiratory complications (pneumonia and ventilator support) and reoperation.
Results: Out of 27,777 patients who underwent elective EVAR, 9,258 (33.3%) were anemic (Mild:87.3%, moderate/severe:12.7%). Tx was carried out in 20.4% (n=1,887) of anemic patients:8.1% received pre/intra-operative transfusion, 8.6% postoperative and 3.7% received both. The median units of pRBC transfused was 2(IQR:1-3). In patients with mild and moderate/severe anemia, perioperative Tx was associated with increased rates of in-hospital and 30-day mortality, as well as other in-hospital complications(Table1). After adjusting for patientsí demographics, comorbidities(Diabetes, HTN, CAD, CHF, COPD, CKD), preoperative medications as well as aneurysm diameter, intraoperative blood loss and concomitant procedures, perioperative Tx was associated with increased in-hospital adverse events [OR (95%CI: mild anemia: 4.3(3.5-5.3), moderate/severe anemia:3.4(2.5-4.7) (both P<0.001). A linear relationship was noted between the odds of adverse outcomes after Tx and preoperative Hb levels (Figure).In addition, subgroup analysis showed that anemic patients transfused with more than 3 units of pRBC had higher odds of adverse events compared to those receiving less than 3 units [OR(95%CI): mild anemia: 4.2 (2.60-6.85), moderate/severe anemia:2.9(1.57-5.39)] (both P<0.05).
Conclusion: This study shows that perioperative Tx is not the optimal approach to manage anemic patients undergoing elective EVAR. Minimizing the number of pRBC units might reduce the risk of adverse event when Tx is absolutely necessary.However,medical management of anemia may be warranted in these patients to reduce morbidity and mortality.

Table 1. Comparison of Outcomes of Anemic EVAR patients Receiving Peri-Operative Blood Transfusion v
Mild AnemiaModerate/Severe Anemia
No TranfusionTranfusionp-valueNo TranfusionTranfusionp-value
Primary Outcomes, n (%)
In-hospital Mortality30 (0.4)45 (3.6)<0.0017 (1.3)30 (4.8)<0.01
Myocardial infarction (MI)
Troponin only31 (0.45)35 (2.8)<0.0012 (0.4)18 (2.9)<0.01
EKG or Clinical14 (0.2)27 (2.2)6 (1.1)6 (1.0)
Total MI45 (0.7)62 (5.0)8 (1.5)24 (3.8)0.02
CHF46 (0.7)59 (4.7)<0.0018 (1.5)33 (5.2)<0.001
Dysrhythmia137 (2.0)113 (9.1)<0.00113 (2.4)36 (5.7)0.01
Stroke10 (0.15)16 (1.3)<0.0012 (0.4)1 (0.2)0.60
Renal Complications199 (3.0)184 (15.1)<0.00125 (4.7)114 (18.6)<0.001
Bowel Ischemia12 (0.2)28 (2.2)<0.0014 (0.7)12 (1.9)0.13
Leg Ischemia35 (0.5)36 (2.9)<0.0016 (1.1)23 (3.7)0.01
Respiratory Complication (Pneumonia or Ventilator)78 (1.1)96 (7.7)<0.00110 (1.9)49 (7.8)<0.001
Reoperation68 (1.0)121 (9.7)<0.00116 (3.0)63 (10.0)<0.001
Composite In-Hospital Outcomes502 (7.4)411 (32.9)<0.00164 (11.8)210 (33.2)<0.001
Secondary Outcomes
Length of Stay (days), median (IQR)1 (1-2)4 (2-7)<0.0012 (1-3)4 (2-7)<0.001
ICU Stay (days), median (IQR)0 (0-1)1 (0-2)<0.0010 (0-1)1 (0-3)<0.001
Procedure Time (min), mean (SE)129 (58.4)205 (101.3)<0.001134 (74.4)176 (88.8)<0.001
Mortality (30-day)60 (0.9)60 (4.8)<0.00110 (1.9)43 (6.8)<0.001

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